1. Field of the Invention
The present disclosure relates to a method of producing a positive electrode active material for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.
2. Description of Related Art
In recent years, mobile equipment such as VTRs, mobile phones and notebook personal computers has been prevailing and has been reduced in size, and as an electric power supply source therefor, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery has come to be used. Furthermore, from an aspect of dealing with recent environmental problems, the battery has also been attracting attention as a battery for motive power of an electric vehicle or the like.
As a positive electrode active material for a lithium secondary battery, a lithium-cobalt composite oxide, which is one capable of constituting a 4 V class secondary battery, has been generally and widely employed.
Since cobalt, which is a raw material of LiCoO2, is a scarce resource and unevenly distributed, cobalt is available at a high cost and the raw material supply is unstable.
Responding to these circumstances, a lithium-transition metal composite oxide with a layered structure, such as a lithium-nickel-cobalt-manganese composite oxide, in which a part of Co in LiCoO2 is substituted with an element such as Ni, Mn or the like has been developed.
There is a technique for coating the surface of lithium-transition metal composite oxide particles with a compound of various elements to impart an additional specific function. Examples of the element used for coating also include a rare earth element and fluorine.
In JP 2008-536285 T, there is disclosed a positive electrode active material prepared by coating the surface of a lithium-transition metal composite oxide such as lithium-cobalt composite oxide with a fluorine compound such as lithium fluoride. It has been reported that the deterioration in cycle characteristics at high voltages and high rates can be prevented by such a constitution.